Add events to listen on process start / end for task executions.

src/vs/workbench/api/shared/tasks.ts

@@ -88,6 +88,17 @@ export interface TaskExecutionDTO {
 	task: TaskDTO;
 }
 
+export interface TaskProcessStartedDTO {
+	id: string;
+	processId: number;
+}
+
+export interface TaskProcessEndedDTO {
+	id: string;
+	exitCode: number;
+}
+
+
 export interface TaskFilterDTO {
 	version?: string;
 	type?: string;